How to detect the PR of the PPT sharing sites that you have listed above.

if you use browsers like Firefox or Chrome - and that you should use in this area - there are so many extensions and addons wich makes everything more easy in the online, as "Seo for Chrome" extension or "iSEO - Seo for Chrome", which shows in the top-right corner the PR for every page, also "seo analysis tool", but just go to the google chrome store and search "PR checker addon" and install them quickly...